Fire extinguisher

ABSTRACT

A fire extinguisher including a body extending along a longitudinal axis and defining a storage chamber wherein a load of an extinguishing agent is present, and also a pressurizing chamber including a pyrotechnic gas generator, the pressurizing chamber being separated from the storage chamber by a perforated wall configured to put an outlet of the pyrotechnic gas generator into communication with the storage chamber, the perforated wall defining an end of the storage chamber, the extinguisher having a discharge channel configured to deliver the extinguishing agent to the outside of the extinguisher during actuation of the pyrotechnic gas generator, the discharge channel opening out into the storage chamber through an opening positioned at a distance from the perforated wall, as measured along the longitudinal axis of the body, that is less than or equal to half the length of the storage chamber.

BACKGROUND OF THE INVENTION

The invention relates to a fire extinguisher including a pyrotechnic gasgenerator.

A fire extinguisher is conventionally in the form of a tank containingan extinguishing agent that is to be delivered onto the zone of a firein order to extinguish it. Several types of extinguisher are known inthe state of the art.

In particular, extinguishers are known that are permanently pressurized,comprising a tank under gas pressure containing the extinguishing agent,or else a gas cylinder under pressure in communication with the chamberin which the extinguishing agent is present. In that type ofextinguisher, the extinguishing agent or the propellant gas forpropelling the extinguishing agent is stored permanently under pressure.In order to use extinguishers having a pressurized gas cylinder, the gascylinder is initially actuated by the user in order to release thepressurizing gas into the chamber containing the extinguishing agent,and then the extinguishing agent as put under pressure in this way isdelivered onto the fire zone by manual actuation.

Extinguishers that are permanently pressurized present certaindrawbacks, such as in particular the need for a certain number ofmonitoring and verification operations (periodic weighing). In addition,since the pressure of gas varies with temperature, the operation ofextinguishers of that type is temperature-sensitive.

Another drawback is that while delivering the extinguishing agent, thevolume available for the gas increases and thus the pressure of the gasdecreases, thereby reducing the rate at which the extinguishing agent isdelivered, and consequently reducing the effectiveness of theextinguisher. In an attempt to mitigate that drawback, it is possible toincrease the pressure available at the beginning of delivering theextinguishing agent, however for safety reasons such a solution makes itnecessary to overdimension the extinguisher, and consequently toincrease its overall size and also its cost price.

As an alternative to extinguishers that are permanently pressurized, asecond type of extinguisher has been proposed that includes apyrotechnic gas generator. The pyrotechnic gas generator enablescombustion gas to be produced that serves to pressurize the chamber inwhich the extinguishing agent is present, and consequently to deliversaid extinguishing agent onto the fire zone. Such extinguishers with apyrotechnic gas generator give relatively high performance and serve tomitigate some of the drawbacks of extinguishers with permanentpressurization.

In particular, Document DE 20 2006 002 892 discloses an extinguisherhaving a pyrotechnic gas generator presenting architecture that isrelatively close to the architecture of permanently pressurizedextinguishers that make use of a cylinder of gas under pressure. In thatdocument, the gas generator is actuated by a manual striker situated atone end of the tank and it communicates with the load of extinguishingagent via a first dip tube. A second dip tube is connected to the outletorifice and serves to direct the extinguishing agent towards the outletorifice. A lance having a trigger communicates with the outlet orificeand enables the extinguishing agent to be delivered into the outsidemedium after actuation by a user.

The extinguisher of Document DE 20 2006 002 892 presents certainadvantages, but nevertheless it would still be desirable to be able tosimplify its structure, in particular in order to reduce the cost offabricating such an extinguisher. Furthermore, the rate at which theextinguishing agent is delivered is not always optimal in that type ofextinguisher.

There thus exists a need to have fire extinguishers available thatpresent a structure that is simplified and a fabrication cost that isreduced.

There also exists a need to have fire extinguishers available thatpresent an optimized flow rate for delivering the extinguishing agent.

OBJECT AND SUMMARY OF THE INVENTION

To this end, in a first aspect, the invention provides a fireextinguisher comprising a body extending along a longitudinal axis anddefining a storage chamber in which a load of an extinguishing agent ispresent, and also a pressurizing chamber comprising a pyrotechnic gasgenerator, the pressurizing chamber being separated from the storagechamber by a perforated wall configured to put an outlet of thepyrotechnic gas generator into communication with the storage chamber,the perforated wall defining an end of the storage chamber, theextinguisher having a discharge channel configured to deliver theextinguishing agent to the outside of the extinguisher during actuationof the pyrotechnic gas generator, said discharge channel opening outinto the storage chamber through an opening positioned at a distancefrom the perforated wall, as measured along the longitudinal axis of thebody, that is less than or equal to half the length of the storagechamber.

The pyrotechnic gas generator is configured to produce a combustion gasthat flows into the storage chamber through the outlet of said gasgenerator and the perforated wall so as to put the storage chamber underpressure. The discharge channel is configured to enable theextinguishing agent to be delivered into the medium outside theextinguisher as a result of the storage chamber being put under pressureby the combustion gas.

The extinguisher of the present invention presents a particulararrangement in which firstly there is separation between the compartmentcontaining the gas generator and the compartment containing theextinguishing agent, and secondly the discharge channel is positioned ina manner that is relatively close to the end of the storage chamber. Theinventors have observed that this particular arrangement servesadvantageously to provide a high-performance extinguisher that enablesthe majority or even substantially all of the weight of the load ofextinguishing agent to be delivered, while presenting a structure thatis simplified in which the use of dip tubes in the storage chamber ismade superfluous. As a result, the invention provides an effective fireextinguisher presenting a fabrication cost that is significantlysmaller, in particular compared with the extinguishers described in DE20 2006 002 892.

In an embodiment, the extinguisher may also further comprise a firstshutter shutting the discharge channel in sealed manner, said firstshutter being configured to enable the extinguishing agent to exit tothe outside of the extinguisher through the discharge channel when thepressure in the storage chamber exceeds a predefined value.

As mentioned above, the rate at which the extinguishing agent isdelivered is not always optimum when using an extinguisher of the kindtaught in Document DE 20 2006 002 892. The inventors have observed thatthe problem that can be encountered by an extinguisher of that typemaking use of manual actuation is that, at the moment when the useractuates opening of the outlet orifice, the pressure inside the tank canhave reduced significantly. Specifically, the gas generated by thepyrotechnic gas generator is hot and the tank pressurizing effect isthus more temporary as a result of the gas cooling than is thepressurizing effect obtained when using a gas cartridge that deliverscold gas. It is therefore advantageous not to delay expelling theextinguishing agent as a result of actuation being manual, as can happenin the architecture of Document DE 20 2006 002 892. Thus, the aboveconfiguration using a first shutter serves advantageously to optimizethe rate at which the extinguishing agent is delivered by theextinguisher since, as soon as a predetermined pressure threshold isreached in the storage chamber, the first shutter acts automatically(i.e. without requiring any actuation by a user) to allow theextinguishing agent to be delivered to the outside of the extinguisher.Such a configuration serves advantageously to make best use of the extrapressure generated by the gas generator in order to deliver theextinguishing agent and it avoids the problem of user actuation thatmight take place at an instant when the extra pressure in the tank hasalready decreased significantly. Such a configuration thus makes itpossible advantageously to make best use of the advantages procured by apyrotechnic gas generator compared with a gas cartridge, whichadvantages are associated with the capacity to generate gas with asuitable time profile for its flow rate, unlike a gas cartridgegenerating a flow rate profile that decreases drastically.

In an embodiment, the perforated wall may include at least oneperforation and the extinguisher may also include a second shuttershutting said at least one perforation in sealed manner, said secondshutter being configured to act, under the effect of the pressure of acombustion gas produced by the gas generator, to enable said gas to flowinto the storage chamber through said at least one perforation.

The presence of the second shutter is advantageous in order to isolateand protect the gas generator, so as to prevent said gas generator beingpolluted by the extinguishing agent.

In an embodiment, the opening may be situated in a side wall of thebody.

In an embodiment, the distance between the opening and the perforatedwall may be less than or equal to one-fourth of the length of thestorage chamber.

Such a configuration serves advantageously to further increase thefraction of the load of extinguishing agent that can be delivered by theextinguisher in operation.

In an embodiment, the distance between the opening and the perforatedwall may be less than or equal to the inside diameter of the storagechamber.

The diameter of the storage chamber corresponds to the greatesttransverse dimension of the storage chamber.

Such a configuration serves advantageously to further increase thefraction of the load of extinguishing agent that can be delivered by theextinguisher in operation.

In a variant, the discharge channel may pass through the pressurizingchamber and the opening may be situated in the perforated wall. Thus, inan embodiment of the invention, the opening may be positioned at zerodistance from the perforated wall.

Such a configuration serves advantageously to provide an extinguishercapable of delivering a particularly high fraction of the load ofextinguishing agent.

In particular, the pressurizing chamber may be situated between theperforated wall and an end wall of the body, the discharge channel alsopassing through the end wall. In a variant, the discharge channel passesthrough the perforated wall, the pressurizing chamber, and the side wallof the body level with the pressurizing chamber.

In an embodiment, the ratio [length of the storage chamber]/[insidediameter of the storage chamber] may be less than or equal to 10.

Such a configuration serves advantageously to further increase thefraction of the load of extinguishing agent that can be delivered by theextinguisher in operation.

In an embodiment, the perforated wall may present a plurality ofperforations distributed around the longitudinal axis of theextinguisher.

In an embodiment, the extinguishing agent may be in powder form. In avariant, the extinguishing agent may be in some other form, e.g. in theform of a foam.

In an embodiment, the gas generator may include at least one housingcontaining a pyrotechnic charge, said pyrotechnic charge presenting athrough channel.

The presence of such a through channel in the pyrotechnic charge servesadvantageously to control the rate at which gas is generated duringcombustion of said charge, and possibly even to make that rate constant.

In an embodiment, the gas generator may include a plurality of housings,each containing a pyrotechnic charge, said housings being positionedaround the longitudinal axis of the body. In addition, the housings maybe positioned around an igniter device configured to ignite thepyrotechnic charges present in said housings.

Such configurations serve advantageously to provide a gas generator ofstructure that is relatively compact.

The present invention also provides a vehicle fitted with anextinguisher as described above.

In particular, the vehicle may be a bus. In an embodiment, theextinguisher may be incorporated in a vehicle so as to enable a fire tobe extinguished in the engine of said vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention appear from thefollowing description of particular embodiments of the invention, givenas non-limiting examples, and with reference to the accompanyingdrawings, in which:

FIG. 1 shows an example extinguisher of the invention;

FIG. 2 is a fragmentary longitudinal section of the FIG. 1 extinguisher;

FIG. 3 shows a detail of the FIG. 1 extinguisher;

FIG. 4 shows the operation of the FIG. 1 extinguisher;

FIG. 5 shows another example of an extinguisher of the invention;

FIG. 6 shows the operation of the FIG. 5 extinguisher; and

FIG. 7 shows a variant of the pyrotechnic gas generator usable in theexample of FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows an example fire extinguisher 1 of the invention. Theextinguisher comprises a body 2 extending along a longitudinal axis Xand defining a storage chamber 4 in which a load (not shown) of anextinguishing agent is present. In the example shown, the extinguishingagent is in the form of a powder, which powder may for example be anypowder that is known for being useful in extinguishing fires of classesA, B, or C. As mentioned above, the invention covers using anextinguishing agent in other forms, such as a foam. It is advantageousfor the extinguishing agent to be in the form of a powder that is notcompacted, as described in detail below. The body 2 also defines apressurizing chamber 5 containing a pyrotechnic gas generator. Thepressurizing chamber 5 is separated from the storage chamber 4 by aperforated wall 7 that is configured to put an outlet of the pyrotechnicgas generator into communication with the storage chamber 4. In theexample shown, the body 2 presents the shape of a body of revolution,specifically a cylinder. Naturally, the invention is not limited to suchshapes for the body 2. The body 2 comprises a side wall 2 a extendingalong the longitudinal axis X of the body 2 and surrounding the storagechamber 4. The side wall 2 a of the body also surrounds the pressurizingchamber 5. The body 2 also includes a bottom end wall 2 b and a top endwall 2 c. The bottom end wall 2 b and the top end wall 2 c define thebody 2 longitudinally. The pressurizing chamber 5 is situated betweenthe perforated wall 7 and the bottom end wall 2 b of the body 2. Thestorage chamber 4 is situated between the top end wall 2 c of the body 2and the perforated wall 7, which wall defines a bottom of the storagechamber 4. In order to improve the quantity of extinguishing agentdelivered by the extinguisher by enhancing the creation of a fluidizedbed during actuation of the pyrotechnic gas generator, the ratiol_(s)/D, where D is the inside diameter of the storage chamber 4 andl_(s) is the length of the storage chamber measured along thelongitudinal axis X, may advantageously be less than or equal to 10,e.g. less than or equal to 6, e.g. less than or equal to 5. This ratiol_(s)/D may be greater than or equal to 3. The length l_(s) of thestorage chamber 4 may lie in the range 45 centimeters (cm) to 90 cm, forexample. The inside diameter D of the storage chamber 4 may, forexample, lie in the range 10 cm to 20 cm, e.g. it may be substantiallyequal to 15 cm.

FIG. 2 is a fragmentary section on the longitudinal axis X of the FIG. 1extinguisher 1. FIG. 2 shows in greater detail the arrangement of thepressurizing chamber 5. As shown, the pressurizing chamber 5 contains apyrotechnic gas generator 20 that is configured to produce a combustiongas in order to pressurize the storage chamber 4. In the example shown,the gas generator 20 has a plurality of housings 22, each of thesehousings 22 including a pyrotechnic charge 23. The gas generator 20 alsoincludes an igniter device 25 configured to ignite the pyrotechniccharges 23 present in the housings 22. The gas generator 20 may betriggered electrically by applying an electric current to the terminalsof the initiator (as shown in FIG. 2) or it may be triggeredmechanically (triggering by percussion). With mechanical triggering, astriker strikes the igniter device. Under all circumstances, initiatingthe ignition device 25 leads to combustion of the central charge 27,which in the example shown is in the form of stacked blocks, therebyleading to combustion of the pyrotechnic charges 23 and to release ofthe gas resulting from the combustion. It would not go beyond the ambitof the present invention for the gas generator 20 to have a singlehousing fitted with its pyrotechnic charge.

The pyrotechnic charges 23 may be in the form of monolithic blocks,possibly possessing at least one open channel, as described in detailbelow. In a variant, the pyrotechnic charges 23 may be in the form of agranular material. Naturally, it is possible to have a single gasgenerator containing a first fraction of pyrotechnic charges that are inthe form of monolithic blocks and a second fraction of pyrotechniccharges that are in the form of a granular material.

The pyrotechnic charges 23 used in the gas generator 20 of theextinguisher 1 may have the same composition as the pyrotechnic chargestypically used in gas generators for airbags. Naturally, the pyrotechniccharges 23 present dimensions adapted to the intended operating duration(i.e. bigger than those of the pyrotechnic charges used in gasgenerators for airbags). Pyrotechnic compositions suitable for use inthe gas generator of the extinguisher of the invention are described inparticular in the following documents: U.S. Pat. Nos. 5,608,183,6,143,102, FR 2 975 097, FR 2 964 656, FR 2 950 624, FR 2 915 746, FR 2902 783, FR 2 899 227, FR 2 892 117, FR 2 891 822, FR 2 866 022, FR 2772 370, and FR 2 714 374. By way of example, the gas generator may haveat least five pyrotechnic charges 23, e.g. at least ten pyrotechniccharges, e.g. at least twenty pyrotechnic charges.

The extinguisher 1 also presents a discharge channel 12 configured todeliver the extinguishing agent to the outside of the extinguisher 1when the pyrotechnic gas generator 20 is in action. In the example shownin FIG. 2, the channel 12 passes through the pressurizing chamber 5 andthe perforated wall 7 and opens out directly in the storage chamber 4.Thus, the channel 12 opens out in the storage chamber 4 through anopening 12 a situated in the perforated wall 7. Under suchcircumstances, the opening 12 a is positioned at a zero distance fromthe perforated wall, and thus at a distance that is necessarily lessthan or equal to half the length of the storage chamber. The channel 12also passes through the bottom end wall 2 b of the body 2. Theextinguisher 1 is configured to deliver the extinguishing agent when thepyrotechnic gas generator is actuated through an outlet orifice 10situated in the bottom end wall 2 b of the body. Thus, in the exampleshown in FIG. 2, the channel 12 presents a first end opening out intothe storage chamber 4, which end is constituted by the opening 12 a, anda second end opening out to the outside of the extinguisher 1, whichopening is constituted by the outlet orifice 10. In the example shown,the channel 12 extends along the longitudinal axis X of the body. By wayof example, the channel 12 may present a diameter D1 (i.e. its greatesttransverse dimension) lying in the range 20 millimeters (mm) to 40 mm.In a variant that is not shown, it is possible for the outlet orifice tobe present in the side wall of the body at the level of the pressurizingchamber and for said orifice to communicate in the same manner with thestorage chamber via a channel passing through the pressurizing chamberand the perforated wall and opening out directly into the storagechamber.

The extinguisher 1 also has a first shutter 15 shutting the dischargechannel 12 in sealed manner, the first shutter 15 being configured toenable the extinguishing agent to exit to the outside of theextinguisher 1 through the channel 12 when the pressure in the storagechamber 4 exceeds a predefined value. In other words, the first shutter15 is configured, when in a first configuration, to prevent theextinguishing agent exiting to the outside to the outside of theextinguisher 1, and it is also configured to pass into a secondconfiguration when the pressure in the storage chamber 4 exceeds apredefined value, this second configuration of the first shutter 15allowing the extinguishing agent to exit to the outside of theextinguisher 1. By way of example, the first shutter 15 may be in theform of a diaphragm configured to yield when the pressure in the storagechamber 4 exceeds a predefined value. Under such circumstances, and byway of example, the first shutter 15 may be a diaphragm made of aluminumor of an alloy of the Inconel® type. In a variant, the first shutter 15may be configured to move without yielding when the pressure in thestorage chamber 4 exceeds a predefined value, thereby enabling theextinguishing agent to exit to the outside of the extinguisher throughthe discharge channel 12 and the outlet orifice 10. Under suchcircumstances, and by way of example, the first shutter 15 may be in theform of a valve, e.g. in the form of a spring-loaded valve. As mentionedabove, the presence of the first shutter is advantageous for avoidingany need for a user to actuate delivery of the extinguishing agent tothe outside of the extinguisher. This serves advantageously to optimizethe flow of extinguishing agent delivered by the extinguisher.

It would not go beyond the ambit of the present invention for theextinguisher to have a plurality of discharge channels, with some or allof these channels not being provided with a first shutter as describedabove. Nor would it go beyond the ambit of the invention if theextinguisher does not have any such first shutter. Under suchcircumstances, the delivery of the extinguishing agent to the outside ofthe extinguisher is actuated by a user.

FIG. 3 shows the perforated wall 7 in greater detail. The perforatedwall 7 separates the pyrotechnic gas generator from the extinguishingagent present in the storage chamber. The perforated wall 7 isconfigured to put an outlet of the pyrotechnic gas generator intocommunication with the storage chamber. As shown, and by way of example,the perforated wall 7 may be in the form of a plate having a pluralityof perforations 8 configured to allow a combustion gas produced by thepyrotechnic gas generator to flow into the storage chamber. Theperforated wall 7 presents a plurality of perforations 8 distributedaround the longitudinal axis X of the body 2 of the extinguisher 1. Inthe example shown, the flow direction of the combustion gas through theperforated wall is substantially parallel to the longitudinal axis ofthe body. In an embodiment, the perforations 8 act as nozzles for thegas generator. The perforated wall 7 extends transversely, e.g.perpendicularly, relative to the longitudinal axis of the body.

Some or all of the perforations 8 in the perforated wall 7 may be shutin sealed manner prior to first use of the extinguisher 1 by means of asecond shutter 30 that is configured, under the effect of the pressureof the combustion gas produced by the gas generator, to allow said gasto flow into the combustion chamber through the perforations. By way ofexample, the second shutter 30 may be in the form of a diaphragm thatmay be situated in the storage chamber and cover the perforated wall 7,or that may be situated in the pressurizing chamber. This diaphragm maybe in contact with the perforated wall 7. By way of example, thediaphragm may be formed by a plastics material such as polyethyleneterephthalate or such as an adhesive metal film such as a film ofaluminum or of tin so as to operate in shear when subjected to pressureby the pyrotechnic gas generator. The diaphragm may advantageously beadhesively bonded on the perforated wall 7. The second shutter 30 may besuitable for yielding under the effect of the pressure of the combustiongas produced by the gas generator in order to allow said gas to flowinto the storage chamber. The presence of the second shutter 30 isadvantageous for isolating and protecting the gas generator, therebypreventing said generator being polluted by the extinguishing agent andgiving better control over the ignition of the pyrotechnic charge(s).Naturally, it would not go beyond the ambit of the present invention forthe extinguisher not to have such a second shutter 30.

Thus, and as shown in particular in FIGS. 1 to 3, the extinguisher 1does not have a dip tube extending into the load of extinguishing agentfor the purpose of transporting the extinguishing agent towards theoutlet orifice. Likewise, the extinguisher 1 does not have a dip tubeextending in the load of extinguishing agent and serving to transportthe combustion gas produced by the gas generator into the load ofextinguishing agent. Thus, the invention serves advantageously toprovide extinguishers presenting a number of components that is reducedcompared with the prior art and thus to have structures that are lighterin weight and less expensive, with efficiency that is at least equal.

The operation of the extinguisher 1 described with reference to FIGS. 1to 3 is described below.

Actuating the pyrotechnic gas generator serves to cause one or morepyrotechnic charges to combustion and thereby generate combustion gas.Under the effect of the pressure of the combination gas the secondshutter gives way so as to enable the combustion gas to flow through theperforated walls to the storage chamber and come into contact with theextinguishing agent. The combustion gas thus serves to put the storagechamber under pressure. In the storage chamber, the load ofextinguishing agent may be in the form of a powder, as mentioned above.The powder may advantageously present apparent density lying in therange 40% to 55% of its theoretical density. When the combustion gaspenetrates into the storage chamber, such values for the apparentdensity of the powder serve advantageously to create a fluidized bedthat enhances delivery of the extinguishing agent to the outside of theextinguisher. Once a predefined value has been reached for the pressurein the storage chamber, the first shutter goes into a secondconfiguration enabling the extinguishing agent to exit to the outside ofthe extinguisher through the discharge channel and the outlet orifice.The predefined pressure value in the storage chamber at which the firstshutter goes into the second configuration may be greater than or equalto 20 bars, or even 40 bars. The time during which the extinguishingagent is discharged to the outside of the extinguisher may be greaterthan or equal to 1 second, or 5 seconds, or indeed 10 seconds, forexample. In an advantageous variant, the gas generator continues tooperate after the first shutter has gone into the second configuration.That serves advantageously to increase the fraction of the extinguishingagent that is discharged to the outside of the extinguisher. In avariant, the gas generator stops operating when the first shutter goesinto the second configuration. As mentioned above, the arrangement shownserves advantageously to avoid the outlet orifice becoming blocked withthe extinguishing agent, and thus enables a significant fraction of theextinguishing agent to be discharged to the outside of the extinguisher.In operation, the extinguisher may be horizontal or vertical, and forexample it may be mounted in a vehicle. FIG. 4 shows in highlydiagrammatic manner how the FIG. 1 extinguisher operates. Combustion gaspenetrating into the storage chamber 4 is represented in FIG. 4 by arrowI, and the extinguishing agent exiting to the outside of theextinguisher 1 is represented by arrow S. In the example shown, thedirection in which the combustion gas penetrates into the storagechamber and the direction in which the extinguishing agent exits to theoutside of the extinguisher are both substantially parallel to thelongitudinal axis X of the body 2.

FIG. 5 shows a variant extinguisher 1′ of the invention. In the samemanner as for the extinguisher 1 shown in FIG. 1, the extinguisher 1′comprises a body 2′ defining a storage chamber 4′ in which a load of anextinguishing agent is present, and also a pressurizing chamber 5′containing a pyrotechnic gas generator. The pressurizing chamber 5′ isseparated from the storage chamber 4′ by a perforated wall 7′ configuredto put an outlet from the pyrotechnic gas generator into communicationwith the storage chamber 4′. In the same manner as for the example ofFIG. 1, the perforated wall 7′ presents a plurality of perforations 8′distributed around the longitudinal axis X′ of the body 2′ of theextinguisher 1′. Unlike the example shown in FIG. 1, the dischargechannel 12′ passes through the side wall 2′a of the body. The dischargechannel 12′ opens out into the storage chamber 4′ via an opening 12′apositioned at a distance d from the perforated wall 7′ that is shorterthan or equal to half the length l_(s) of the storage chamber, or indeedone-fourth of this length, or even less, or else equal to the insidediameter D of the storage chamber. As shown in FIGS. 5 and 6, thedistance d corresponds to the distance between the center of the opening12′a and the perforated wall 7′. In the example shown in FIGS. 5 and 6,the channel 12′ has a first end opening out into the storage chamber 4′constituted by the opening 12′a, and a second end opening out to theoutside of the extinguisher 1 and constituted by the outlet orifice 10′.As in the embodiment of FIG. 1, the extinguisher 1′ may optionallyinclude a first shutter and/or a second shutter.

The operation of the extinguisher 1′ shown in FIG. 5 is shown verydiagrammatically in FIG. 6. Combustion gas penetrating into the storagechamber 4′ is represented in FIG. 6 by arrow I, and the exit of theextinguishing agent to the outside of the extinguisher 1′ is representedby arrow S. In the example shown, the combustion gas penetrates into thestorage chamber in a direction that is substantially parallel to thelongitudinal axis X′ of the body 2′, and the extinguishing agent exitsin a direction S to the outside of the extinguisher that issubstantially perpendicular to the longitudinal axis X′ of the body 2′.

FIG. 7 shows a variant pyrotechnic gas generator 20′ suitable for use inthe example of FIG. 1. The gas generator 20′ comprises a plurality ofhousings 22, each containing a pyrotechnic charge 23, the housings 22being positioned around the longitudinal axis of the body of theextinguisher. As shown, the housings 22 extend radially (perpendicularlyrelative to the longitudinal axis of the body). The example shown inFIG. 7 comprises a first group of housings superposed on a second groupof housings, the housings of the first group being present at a firstheight in the body and the housings of the second group being present ata second height in the body that is different from the first height.Naturally, it would not go beyond the ambit of the invention for thepyrotechnic gas generator to have a single group of housings positionedaround the longitudinal axis of the body of the extinguisher, saidhousings all being present at the same height in the body. In theexample of FIG. 7, the housings 22 are positioned around the igniterdevice 25 configured to ignite the pyrotechnic charges 23 present insaid housings. The igniter device 25 presents radial orifices, eachorifice being situated facing a pyrotechnic charge 23. As shown in FIG.7, the igniter device 25 is present in a central portion of thepyrotechnic gas generator 20′. In addition, as shown in FIG. 7, some orall of the pyrotechnic charges 23 may present an open channel 24. Eachchannel 24 opens out at two opposite ends of a pyrotechnic charge 23.The presence of such a channel passing through the pyrotechnic chargeserves advantageously to control the rate at which gas is generatedduring combustion of said pyrotechnic charge, and possibly even to makethis rate constant. The gas generator 20′ shown in FIG. 7 advantageouslypresents a structure that is relatively compact occupying little space.Naturally, it is possible in a variant to avoid having a channel 12present and to incorporate a pyrotechnic gas generator of the same typeas in the extinguisher in the example shown in FIG. 5.

The term “lying in the range . . . to . . . ” should be understood asincluding the bounds.

The invention claimed is:
 1. A fire extinguisher comprising: a bodyextending along a longitudinal axis and defining a storage chamberwherein a load of an extinguishing agent is stored, the storage chamberhaving an upper surface defining a top end of the storage chamber, and alower surface defining a bottom end of the storage chamber, the uppersurface and lower surface being positioned at opposite ends of thestorage chamber along the longitudinal axis; a pressurizing chamberincluding a pyrotechnic gas generator; a perforated wall that separatesthe pressurizing chamber from the storage chamber, the perforated wallis configured to put an outlet of the pyrotechnic gas generator intocommunication with the storage chamber, the perforated wall being thelower surface that defines the bottom end of the storage chamber at alongitudinal end of the storage chamber; and a discharge channelconfigured to deliver the extinguishing agent to the outside of theextinguisher during actuation of the pyrotechnic gas generator, whereinsaid discharge channel opens out into the storage chamber through anopening positioned at a distance from the perforated wall, as measuredalong the longitudinal axis of the body, that is less than or equal tohalf the length of the storage chamber.
 2. The extinguisher according toclaim 1, further comprising a first shutter shutting the dischargechannel in sealed manner, said first shutter being configured to enablethe extinguishing agent to exit to the outside of the extinguisherthrough the discharge channel when the pressure in the storage chamberexceeds a predefined value.
 3. The extinguisher according to claim 1,wherein the perforated wall includes at least one perforation and theextinguisher also includes a second shutter shutting said at least oneperforation in sealed manner, said second shutter being configured toact, under the effect of the pressure of a combustion gas produced bythe gas generator, to enable said gas to flow into the storage chamberthrough said at least one perforation.
 4. The extinguisher according toclaim 1, wherein the discharge channel passes through the pressurizingchamber and the opening is situated in the perforated wall.
 5. Theextinguisher according to claim 4, wherein the pressurizing chamber issituated between the perforated wall and an end wall of the body, thedischarge channel also passing through the end wall.
 6. The extinguisheraccording to claim 1, wherein the opening is situated in a side wall ofthe body.
 7. The extinguisher according to claim 1, wherein the distance(d) between the opening and the perforated wall is less than or equal toone-fourth of the length (□s) of the storage chamber.
 8. Theextinguisher according to claim 1, wherein the distance (d) between theopening and the perforated wall is less than or equal to the insidediameter of the storage chamber.
 9. The extinguisher according to claim1, wherein the ratio (length of the storage chamber)/(inside diameter ofthe storage chamber) is less than or equal to
 10. 10. The extinguisheraccording to claim 1, wherein the perforated wall presents a pluralityof perforations distributed around the longitudinal axis of theextinguisher.
 11. The extinguisher according to claim 1, wherein theextinguishing agent is in powder form.
 12. The extinguisher according toclaim 1, wherein the gas generator includes at least one housingcontaining a pyrotechnic charge, said pyrotechnic charge presenting athrough channel.
 13. The extinguisher according to claim 1, wherein thegas generator includes a plurality of housings, each containing apyrotechnic charge, said housings being positioned around thelongitudinal axis of the body.
 14. The extinguisher according to claim13, wherein the housings are positioned around an igniter deviceconfigured to ignite the pyrotechnic charges present in said housings.15. A vehicle fitted with an extinguisher according to claim 1.